Field of the Invention
The present invention relates to wellbore completion. More particularly, the invention relates to an apparatus and method for expanding an anchor in a borehole.
Description of the Related Art
Expandable technology enables a smaller diameter tubular to pass through a larger diameter tubular, and thereafter be expanded to a larger diameter. In this respect, expandable technology permits the formation of a tubular string having a substantially constant inner diameter. When an expandable tubular is run into a borehole, it must be anchored within the borehole at the desired depth to prevent movement of the expandable tubular during the expansion process. Anchoring the expandable tubular within the borehole allows expansion of the length of the expandable tubular in the borehole. During the anchoring operation, an expander tool is typically pushed or pulled through an anchor of the expandable tubular to expand the anchor into contact with the surrounding borehole. The anchor must provide adequate frictional engagement between the expandable tubular and the inner diameter of the borehole to stabilize the expandable tubular against longitudinal axial movement within the borehole during the expansion process of the expandable tubular.
The expandable tubular used to isolate the area of interest is often run into the borehole after previous strings of casing are already set within the borehole. The expandable tubular for isolating the area of interest must be run through the inner diameter of the previous strings of casing to reach the portion of the open-hole borehole slated for isolation, which is located below the previously set strings of casing. Accordingly, the outer diameter of the anchor and the expandable tubular must be smaller than all previous casing strings lining the borehole in order to run through the casing to the depth at which the open-hole borehole exists.
Additionally, once the expandable tubular reaches the open-hole portion of the borehole below the previously run casing, the diameter of the open-hole portion of the borehole is often larger than the inner diameter of the casing liner. After being placed at a desired location, to hold the expandable tubular in place within the open-hole portion of the borehole before initiating the expansion process, the anchor must have a large enough outer diameter to sufficiently fix the expandable tubular at a position within the open-hole borehole before the expansion process begins.
There is a need for an open-hole anchor to support an expandable tubular used to isolate an area of interest within a borehole prior to initiating and during the expansion of the expandable tubular. There is a need for an open-hole anchor which is small enough to run through the previous casing liner in the borehole, capable of expanding to a large enough diameter to frictionally engage the inner diameter of the open-hole borehole below the casing liner, and capable of holding the expandable tubular in position axially and rotationally during the expansion of the length of the expandable tubular.